Acos LTI protocol support

This protocol adds the support for communication between learning management systems that support LTI (Moodle, for example) and ACOS server.

Configuration

Add the following line to the ACOS config file

ltiKeys: {consumerKey: 'key', consumerSecret: 'secret'}

and change the keys. Typically, these keys are required when a new LTI activity is added to learning management systems.